In a high side hermetic compressor all or most of the interior of the shell is at discharge pressure which acts over the oil sump. For a fixed vane or rolling piston compressor the only moving parts, with minor exceptions, exposed to the interior of the compressor are the crankshaft and the parts secured thereto such as the rotor and oil pump. To balance the eccentric forces of the compression process on the shaft, the rotor is normally provided with end rings carrying counterweights. A bore in the shaft, the annular space between the stator and rotor and/or the space(s) between the shell and stator define the discharge path for compressed refrigerant and entrained oil as well as a mechanism for centrifugal separation of the entrained oil. The counterweights which provide balancing forces on the shaft are necessarily asymmetrical and act as fans, with resulting drag forces, while rotating in the discharge gas each providing pressure differences in the shell which can act on the oil sump.